Abstract:
Geomagnetic and seismological measurements were established in Antarctica in 1957 as part of the International Geophysical Year and have continued until present. Geomagnetic data have been recorded continuously but for a gap in the data from 1959 until 1963. Since 1963, the components of the earth’s magnetic field (H, D & Z) and the large variations in this field associated with the arriving ... charged particles which produce magnetic storms and aurora, have in principle been recorded continuously, with the quality improving as various upgrades were done. The instruments are still located at Scott Base. Because the surface volcanic rocks at Scott Base are strongly magnetised, two other sites are used for repeat measurements of the earth's magnetic field - Cape Evans (first measured by Scott’s expedition in 1911) and Lake Vanda (first measured in 1974). The magnetic field is remeasured at these sites approximately every five years. Three component recordings of geomagnetic field variations are made, analysed and transmitted to international databases and individual researchers as appropriate. Seismological data have been recorded since 1957 at Scott Base and since 1986 near Vanda Station in the Dry Valleys (VNDA) .The VNDA program was taken over by the USGS (run out of Albuquerque) in 2002 when US and international institutions linked the Dry Valley seismographs into an international telemetered global seismograph network and analysis system. Three component seismological recordings of ground motion are made and analysed for teleseismic events and the location of earthquakes around the globe. This research project forms part of a global networks of observatory seismographs and magnetometers which provide i) information for the study of earthquakes and earth structure and ii) information on the variation of the earth's geomagnetic field on global and regional scales. A 3 component broadband seismometer (SBA) is still located at Scott Base. It forms a vital part of the global network and in the case of seismological or earthquake studies, the Scott Base seismographs are particularly important as the station lies close to the azimuth of the plate boundary and major active tectonic features through New Zealand. The instrument is operated throughout the year and maintained every year.

2011/2012 We recorded the magnetic field at the Weir site by Lake Vanda, but the site at Astro A is now inaccessible and probably underwater, because the lake level has risen. We established a backup site called C Granite, slightly north-east of Weir, and on the same side of the Onyx River as the refuge huts. The preliminary results indicate that the vertical component, and the total strength of the field are continuing to decline as the South Magnetic Pole moves north. Final results can only be calculated when we have a longer period of magnetic data from the Scott Base observatory, to correct our results for annual changes.

Description:
Incorporated Research Institutions for Seismology - A university consortium sponsored by NSF dedicated to the operation of scientific facilites for the acquisition, management and distribution of feely available seismic data

Quality
INTERMAGNET data are available as magnetograms or as digital data files at the provided GET DATA URL link.

Preliminary data can be downloaded via your browser. These data are generally available for the day previous to the current one. For some of the more remoter observatories data are not available for several days.

... Definitive data in INTERMAGNET CD-ROM/DVD binary format or INTERMAGNET spreadsheet format (IAGA2002) can be downloaded via your browser. These data are available for those observatories who have submitted it for inclusion in the next CD-ROM/DVD and for all CD-ROM/DVDs previously published. Older definitive data are also available on the approporiate CD-ROM/DVD.

Ftp access to INTERMAGNET data is available on request. To request this service please send an e-mail to: webmaster@geolab.nrcan.gc.ca.

Recent data is available on this website. Older data is available on the Magnetic Observatory Definitive Data CDs produced by Intermagnet, or at World Data centres.

SBA and VNDA digital archives are available at IRIS http://www.iris.edu. Phases for those stations will be at the ISC http://www.isc.ac.uk. VNDA early data recorded on 70 mm film chips. A copy is held by USGS Albuquerque Seismological Laboratory.

Seismographs (paper) for SBA for 1961 - 1996 are archived at GNS Science. GNS Science also holds microfilm records from the 1957 SBA station, and seismogram printouts from digital data until about 2004. Please contact Brian Ferris at b.ferris@gns.cri.nz